Servomechanisms have been utilized for automating movements of a work piece. A device for automatically abutting first and second sheets of steel for welding the sheets together to form a metal cabinet is an example.
In some heretofore utilized servo systems, an electrical signal is delivered which is representative of a relative position of the work piece. The signal is compared to an instructional signal and the difference between the signals, if any, is amplified and utilized to actuate power means to drive the work piece to a location at which the difference between the delivered signal and the instructional signal is substantially zero.
Electrical position feedback systems are generally of fragile construction, expensive, often bulky, and are usually constructed for direct control by rotary motion. However, the use of power cylinders is generally preferred in modern servomechanisms.
It is therefore desirable to provide a rugged, relatively inexpensive position feedback system which is directly controlled by linear motion and which is of a construction which decreases the bulk of the servo system. This is accomplished in the apparatus of this invention by utilizing the inductor of French Pat. No. 581,065 and uniquely connecting it to the piston and positioning it within the control cylinder housing.